The proposed research is to conduct chemical and pharmacological studies of as yet uncharted toxins of shellfish poisonings caused by Gonyaulax tamarensis and its related organisms with ultimate goals of deriving preventive measures of PSP toxin antidotes, to study the pharmacological implications for possible therapeutic use, and also to study the metabolic fate of toxins in shellfish. The experiments include the isolation of toxins, a large scale culture of organisms, structure elucidation, immunochemical and pharmacological studies. Some other deleterious dinoflagellates, including Gymnodinium breve, will also be studied.